The patch that taught libpq about allowing multiple target hosts
modified connectDBComplete() with the intent of making the
connect_timeout (if specified) apply per-host, not to the complete
connection attempt. It did not do a very good job though, because
the timeout only gets reset when connectDBComplete() itself detects
a timeout. If PQconnectPoll advances to a new host due to some
other cause, the previous host's timeout continues to run, possibly
causing a premature timeout failure for the new one.
Another thing that I find pretty strange is that it is coded so that,
in event of a timeout detection by connectDBComplete, we give up on the
current connhost entry and advance to the next host, ignoring any
additional addresses we might have for the current hostname. This seems
at best poorly thought through. There's no good reason for libpq to
assume that all the addresses returned by DNS point at the same machine,
or share the same network failure points in between.
Attached is an attempt to improve this. I'll park it in the Sept fest.
Patch does not "git apply", but is ok with "patch -p1". Compiles.
Global "make check" is okay.
Feature works for me, i.e. each target host seems to get at least its
Code looks straightforward enough.
The code suggests that timeout is always 2 or more
if (timeout < 2) timeout = 2;
but doc says "It is not recommended to use a timeout of less than 2
seconds", which is inconsistent. It should read "Timeout is always set to
at least 2 whatever the user asks.".
connect_timeout=2.9 is accepted and considered as meaning 2.
connect_timeout=-10 or connect_timeout=two are also accepted and mean
forever. Probably thanks to "atoi".